Hyperextended knees: Causes, symptoms and treatment

Hyperextended knees

What does it mean to have a hyperextended knee?

Hyperextended knees are a common sports injury. It is when the extended knees go beyond the maximum level of straight causing your knee to go backward. It is of varying severity from mild to severe. Most mild cases may be less painful and lasts only for a short period of time whereas the most severe cases can be so much intense and the pain unimaginable.

Hyperextension of the knees is also called as genu recurvatum. This is a Latin term and in this term, “genu” means the knee and “recurvatum” means to bend back. The commonest cause of genu recurvatum is a sports injury caused by a strong blow to the knee or due to the force following quick deceleration or stop. Hyperextension of the knees can occur to anyone but is more common among athletes and sportsmen because they are more likely to suffer such injuries. In addition, road traffic accidents (RTA) and other accidents can give rise to a similar presentation.

Females have an increased risk of increased joint instability and hence are at a higher risk of knee injury than men, particularly in those women who participate in sports like football, soccer, skiing, or lacrosse.
In hyperextension of the knee, the knee joint bends in the opposite direction resulting in pain, swelling and tissue damage, Due to hyperextension of the knee, structures like the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) or popliteal ligaments may get damaged. It not only damages the ligaments, but also the cartilages that surround the knee joint.

Injuries depend on the severity of the blow to the knee. For instance, a minor sports injury leading to hyperextended knee will damage only a few ligaments, while a strong blow to the knee joint may damage several ligaments and cartilage around the knee joint resulting in a more severe injury.

What are the causes of hyperextension of the knee?

Hyperextension of the knee occurs when too much weight or pressure is applied to the knee joint beyond its normal range leading to soft tissue damage, swelling and tears or strains of the ligaments or cartilages.

Some of the common causes of hyperextension of the knee include:

  • Pushing of the femur or patella bone with excess stress on one or more of the major ligaments.
  • Impact to the front of the knee leading to backward movement of the knee joint will result in a tear or a strain of the anterior cruciate ligament (ACL). Such impact is likely to occur in physical situations like a football player being tackled by the legs.

The mechanism that causes knee hyperextension can predict the severity of the condition. A minor trauma will only cause mild pain and swelling whereas a traumatic experience may cause damage to the ligaments, cartilage and soft tissues around the knee joint.

What are the signs and symptoms of knee hyperextension?

Hyperextension of the knee can occur in varying severities to a person. Therefore the signs and symptoms will also vary.

Signs and symptoms of hyperextended knees depend on several factors which include the athlete’s body, the method of hyperextension and the strength of the knee joint.

Some of the common signs and symptoms of knee hyperextension are:

  • Pain following injury
    Hyperextension of the knee joint will definitely cause some pain localized to that area. The exact location of pain and severity will depend on which structures have been damaged including the 4 ligaments that surround your knee joint.
  • Instability of the knee joint
    Following hyperextension of the knee joint, one may feel as if their knee is less steady or unstable than before or in comparison to the opposite healthy knee.
  • Limited movement of the knee joint
    Hyperextension of the knee is usually followed by intense pain, swelling, and weakness of the knee joint thus reducing the ability to move and limits its range of movement.
  • Swelling of the knee joint
    It is the accumulation of fluid within the knee joint cavity, a common experience after injury to the knee joint. Swelling of the knee joint is also referred to as “Water in the knee”.
  • Bruising of the skin overlying the knee joint
    If a greater force has been applied to the knee joint to cause hyperextension of the knee, then it could be traumatic enough to cause damage to the ligaments, cartilage and other soft tissues which will result in bruising of the knee.

How is hyperextension of the knee diagnosed?

The range in severity of the injury to the knee joint is broad and therefore diagnosis of hyperextension of the knee will vary from one person to another.

For instance, a person who has had a very severe trauma to the knee, then there can be more damage to many structures around the knee joint including the ligaments, cartilages and soft tissues. On the other hand, a person who was only exposed to a minor trauma may only suffer a minor degree of hyperextension of the knee joint with mild swelling, pain and reduced movement of the joint. Thus the diagnosis will greatly vary from each person depending on the degree of trauma and underlying tissue damage.

As with any other condition, diagnosis involves a step by step process and consists of 3 main stages. They are:

  • History
    At your appointment with your doctor, they will first get full details about the trauma you had, the symptoms that followed, and your medical history. If you have had been exposed to a past knee injury, then you are more susceptible to a more serious injury this time.
  • Physical examination
    Once a detailed history is taken, your doctor will move onto do a full physical examination on you. This stage is important as it will help your doctor to identify the severity of the injury and if further investigations are needed to make a diagnosis. During the physical exam, the doctor will observe your knee for swelling and bruising which may indicate a tear in one or more of the ligaments, cartilages or soft tissues. Next, they will assess the range of movement of the knee. He or she will move your leg forward and backward to see if there is any limited movement.
  • Investigations
    This is the final stage in the process of diagnosis. Your doctor may order tests to help them make a diagnosis or to confirm the diagnosis.  Typically, imaging tests are ordered if the injury seems to be very severe. Usually, an MRI or X-ray of the knee joint will be done. Imaging tests are not always needed. Doctors can diagnose the condition alone with your history and physical examination results. However, if your injury is severe enough to go in for surgery, then they may do certain investigations to decide your management plan.

What is the treatment for hyperextension of knees?

Just like for any other soft tissue injury, hyperextension of the knee is also advised to be managed according to the RICE principle. This includes:

  • Rest – Stop the activity that caused hyperextension of the knee and seek medical attention. Avoid doing any high intensity or high impact activities. It is also best to avoid any contact sports until you are completely better. During this period, you can take over the counter pain killers such as non-steroidal anti-inflammatory drugs such as Ibuprofen to reduce the pain and the inflammation.
  • Ice the area – Place an ice pack over the site of injury for about 15 minutes several times a day. This will help to reduce the swelling as well as reduces the pain.
  • Compression – Keep your knee joint compressed with the use of a compression stocking, wrap or an elastic bandage. This will help to keep down the swelling and the pain.
  • Keep your leg elevated – The affected leg should be kept elevated above the level of your heart to reduce the swelling.

Surgery

With extreme hyperextension of the knee, rupture of ligaments, especially the anterior cruciate ligament (ACL) may occur. Injuries to the popliteal or the posterior cruciate ligament can also occur following hyperextension of the knee. Such injuries usually need surgical repair.

Recovering from hyperextension of the knee

If you had a mild to moderate sprain following hyperextension of the knee, you will recover within 2 to 4 weeks. However, for fast recovery, it is important that you rest well and limit activities that may aggravate the condition.

Surgery following a tear in one of the ligaments or cartilages, will lead to full recovery and allows you to return to your normal activities in most of the cases. However, it has a long recovery period as long as 6 months and sometimes may take even more than that.

Following surgery, during the recovery period, it is important for you to follow physiotherapy for rehabilitation to increase the stability and allow the muscles around the injured area to come back to their pre-injury condition. Physical therapy will help you to reduce the long recovery period.

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